From: "trans (Thomas Sawyer)" <transfire@...>
Date: 2012-11-20T03:36:17+09:00
Subject: [ruby-core:49605] [ruby-trunk - Feature #6376] Feature lookup and checking if feature is loaded


Issue #6376 has been updated by trans (Thomas Sawyer).


=begin
@mame Your example would load the library. The request is to know where a library comes from (`(({require_path('ostruct')}))`). As an additional benefit it would allow us to know if a library has been loaded or not. It's nothing to do with catching an load error.
=end

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Feature #6376: Feature lookup and checking if feature is loaded
https://bugs.ruby-lang.org/issues/6376#change-33121

Author: trans (Thomas Sawyer)
Status: Assigned
Priority: Normal
Assignee: mame (Yusuke Endoh)
Category: core
Target version: next minor


$LOADED_FEATURES is useful to know what "files" have been loaded. But it doesn't really tell us what "features" have been loaded. If there where were a way to look-up a load path, without actually loading it then it would be possible to compare that to $LOADED_FEATURES and thus know. e.g.

    require 'ostruct'
    $LOADED_FEATURES #=> [..., "/home/trans/.local/lib/ry/rubies/1.9.3-p125/lib/ruby/1.9.1/ostruct.rb"]

    path = require_path('ostruct') #=> "/home/trans/.local/lib/ry/rubies/1.9.3-p125/lib/ruby/1.9.1/ostruct.rb"
    $LOADED_FEATURES.include?(path)

Of course, it would be nice to also have:

    required?('ostruct')  #=> true

These methods could be class methods of special module, if it's important to keep the Kernel more tidy, e.g. `Ruby.required?('ostruct')`.

I am currently working on a project where I need this (and have a couple of other projects that could use it too) and I've had to implement the whole thing from scratch, which isn't simple, nor fast, nor am I 100% confident that it specs exactly to Ruby's own lookup procedure. So it would be much better if Ruby would expose its lookup functionality.




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